DE3226017A1 - Plastic expanding dowel - Google Patents

Abstract

The essentially sleeve-shaped plastic expanding dowel (1) is composed of a neck region (A) and an expanding region. The expanding region consists at least partially of softer plastic than the neck region (A). During expansion by means of an expansion screw (5) there are thus no excessive pressures which have an adverse effect on the retaining part. In consequence, high anchoring levels are achieved even in retaining parts which are liable to fracture. <IMAGE>

Description

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BERG STAPF * ^

PATENT LAWYERS 3226017

MAUERKIRCHERSTRASSE 45 8000 MUNICH 80

Attorney's File 32 320 July 12, 1982

HILTI Aktiengesellschaft

FL-9494 Schaan Principality of Liechtenstein

PLASTIC EXPANDING DOWEL

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»FW ·! 9 * 82 72 * H Telex; 524-S60BERG d Bank accounts: Bayer. Vereinsbank Munich 4u3100 (BLZ 700 202 10)

Tet »t« Sm * e (esfcte): TefeicOtJteYeT: (089) 983049 Hypo-Bank Munich 4410122850 (BlZ 70020011) Swift Code: HYPO DE MM

Si fvWniftert trowel Inlotec 6350 Gr. Il + III Postscheck Munich 65343-808 (BLZ 70010080)

HILTI AKTIENGESELLSCHAFT IN SCHAAN Principality of Liechtenstein

Plastic expansion anchor

The invention relates to a plastic expansion anchor with a Neck area and a spreading area which can be expanded radially by means of an expansion element.

Known plastic expansion anchors are used for anchoring in Receiving parts of different materials or structures and essentially have a spreading area and a adjoining neck area, the wall thickness of which is smaller than that of the spreading area.

For anchoring, such expansion dowels are inserted into a bore of a receiving part and then into the in the direction of insertion of the expansion anchor tapering central bore of the same driven forward an expansion element. Through this becomes the expansion area having the tapered section of the central bore against the wall of the bore in the receiving part deflected radially.

To ensure adequate anchoring in the sewing parts achieve, the known expansion dowels are made of plastic with relatively high strength. This leads to the disadvantage that with such expansion anchors in brittle or pressure-sensitive Aufnähmetteile during the spreading process the strength of the Recording part is partially exceeded. The resulting partial breakout of the hole in the receiving part affects the hold of the spreading area.

In contrast, the invention creates an expansion dowel with which high anchoring values even in pressure-sensitive receiving parts be achieved.

According to the invention, there is the spread area compared to the Neck area at least partially made of softer plastic.

With an expansion dowel designed in this way, by driving an expansion element, e.g. in the form of an expansion screw, in the central bore of the expansion area deflected radially against the wall of the bore in the receiving part. Thanks to its adaptability to form, the soft expansion area has the property of being partial To prevent pressure peaks in the area of the bore of the receiving part. Borehole parts do not break out - The wall of the hole remains as a fully fledged attack surface.

A particularly wide-ranging adaptability to form of the expansion area to the configuration of the borehole or to the zones adjoining this is achieved through the use of a highly compressible soft plastic achieved in the spreading area. For example, when setting the expansion anchor in brick masonry this benefit is significant. Thanks to the compressibility of the plastic, it comes to during the spreading process clear radial engagement behind the hole passing through the chamber webs of the goat] The·?; increases the axial anchoring value of the expansion anchor is considerable.

The expansion dowel can basically be made of two parts. In this case, the one made of softer plastic becomes Expansion area using mechanical or material-locking means merged with the neck area, which is made of plastic of higher strength, to form a unit. It is also possible to manufacture the expansion dowel from one piece, whereby the material used is a thermoplastic, in particular polyamide, has proven itself.

According to a further proposal, the softer plastic of the expansion area has a foam structure. The foam structure can be achieved with a modified polyamide to which a blowing agent, e.g. nitrogen, is added. For example With an addition of 3 percent by weight of propellant, the weight of the expansion anchor can be reduced by up to 50% can be achieved. Modified polyamide also promotes the softness of the dowel.

One-piece expansion dowels are produced in such a way that the thermoplastic is pressed away from the thinner-walled ones Neck area creating side is introduced into an injection mold. In the removed from the gate, The section of the injection mold that forms the thick-walled expansion area can thus be opened at relatively low pressure develop a foam structure unhindered. In the section having the gate point occurs towards the end of the injection process high pressure, which, in conjunction with the rapid cooling of the thin-walled neck area, creates the training a foam structure is at least largely prevented here.

The injection technique shown allows a controlled transition from the area to soft plastic to be achieved the adjoining area of hard plastic. In a further development of the invention, the softer plastic protrudes the neck area axially. The axial area of the neck area adjoining the neck area expediently consists of

harder or less porous plastic and thus guarantees a good thread grip, good screw guidance and bending stiffness .

The same effect can be achieved with a two-part expansion anchor. The softer plastic advantageously surrounds the harder one Plastic radial. The harder plastic is in the form of a tubular that protrudes from the neck area in the setting direction Approach of the latter is present. The second part of the approach is the softer plastic of the expansion area in the Injection molding process applied.

In the case of an expansion dowel of the type indicated above, the thread engagement of the expansion screw is expedient in the area laid with harder plastic. The central bore is therefore smaller than the inside diameter here The thread diameter of the expansion screw must be measured.

In order to prevent the area used for thread engagement of the expansion screw from bulging when the expansion screw is advanced in To prevent this or to ensure the retention of the thread engagement, this area is, for example, from one Includes support ring made of steel. The latter can also be enclosed in the wall of the dowel during the spraying process. As an alternative measure, the application of ribs and the like reinforcing means on the said area has proven itself.

The invention is explained in more detail below with reference to a drawing which shows exemplary embodiments. Show it:

Fig. 1 An expansion dowel with an expansion element in a longitudinal section,

Fig. 2 shows a section through the expansion anchor

Fig. 1, according to section II-II, '

3 shows another embodiment of an expansion anchor with expansion element in longitudinal section.

The expansion dowel, denoted as a whole by 1, is designed essentially in the form of a sleeve. It is made up of one. Neck area A made from largely homogeneous plastic and from a materially connected in the setting direction Spreading area together. The expansion area has a foam structure with porosity increasing in the setting direction and is therefore softer in terms of material than the neck area A.

The expansion dowel 1 has a central bore 2 in the direction of insertion stepped through with decreasing diameter. On the insertion direction side, the central bore 2 opens into the intersection area of two longitudinal slots 3 in the expansion area. The expansion area has a greater wall thickness than the neck area A. A longitudinally slotted support ring 4 made of steel engages around it a rear area of the spreading area.

Fig. 2 shows, inter alia, the cross section of the support ring s 4.

To set the expansion anchor 1 is in a hole in a receiving part (not shown) introduced. Subsequently, an expansion screw designated overall by 5 is inserted into the central bore 2 driven while turning. A threaded shaft 6 creates a secure thread engagement in the inner narrowed zone of the central bore 2, while a front expansion pin 7 of the expansion screw 5 in the intersection area the longitudinal slots 3 penetrates. The expansion area is thereby against the wall of the expansion anchor 1 receiving Bore deflected radially.

The compressibility or softness of the expansion area consisting of a foam structure ensures that does not destroy the material or the structure of the receiving part

resulting pressures occur. This ensures a high anchoring value for the expansion anchor 1.

The expansion dowel according to FIG. 3 is designated as a whole by 11. It in turn has a neck area labeled A hard plastic. This is followed by a tubular one Approach 12 with a smaller outer diameter. The approach 12 is provided with longitudinal slots 13 (only one is visible), which into the tapered central bore in the area of the attachment 14 come up. Furthermore, the extension 12 carries sawtooth-shaped projections 15 on the shell side. The latter create one non-shifting composite with a jacket ■ 16 made of soft, Plastic with a foam structure. When the sheath 16 is applied by injection molding, it is more foamed Plastic penetrated through the longitudinal slots 13 in the central bore 14, which the functionality of the expansion anchor 11 not affected.

The approach 12 forms together with the casing 16 the Expansion area, which is expanded radially by driving a nail-like expansion element 17 for anchoring. Through the Resilience of the soft casing 16 in turn destroys the material or the structure of the receiving part Pressures prevented.

Claims (1)

HILTI AKTIENGESELLSCHAFT IN SCHAAN Principality of Liechtenstein Claims Plastic expansion anchor with a neck area and an expansion area that can be expanded radially by means of an expansion element, characterized in that the spreading area opposite the neck area (A) consists at least partially of softer plastic. Expansion dowel according to Claim 1, characterized in that the softer plastic is highly compressible. Expansion dowel according to Claim 2, characterized in that the softer plastic has a foam structure. 4. Expansion dowel according to one of claims 1 to 3, characterized characterized in that the softer plastic protrudes axially beyond the neck area (A). 5. Expansion anchor according to one of claims 1 to 4, characterized in that the softer plastic is the harder Plastic surrounds radially.